hf brass (broadcast and ship to shore): legacy and … brass (broadcast and ship to shore): legacy...
TRANSCRIPT
HF BRASS (Broadcast and Ship to Shore):Legacy and Modern Approaches
Steve Kille
CEO
12/02/2015
Isodei
Slide 2 of 24 Isodei
Overview
NICE PICTURE
Why deployed BRASS uses Ancient Technology
What is BRASS and why it is Useful
How Legacy BRASS works
New HF Approaches for BRASS
The Isode approach to moving things forward
Slide 3 of 24 Isodei
BRASS: Broadcast
Messages are transmitted from shore station to all ships
Continuous Broadcast
Slide 4 of 24 Isodei
BRASS: Ship to Shore & Ship to Ship
Ship to Shore & Ship to Ship (usually) use STANAG 5066 ARQ
Alternating Transmissions
Messages one way; STANAG 5066 Acks back
Ship to Shore sends:
Messages From Ship
Resend Requests for Broadcast
Maritime Rear Link (MRL) has same topology as ship to shore, but messages sent both ways
Slide 5 of 24 Isodei
BRASS: Why Separate Transmit & Receive Sites
HF Receivers do not like to be close to HF Transmitters
A few miles of separation allows simultaneous operation
Separate Transmit and Receive sites allow
Multiple Broadcast Transmit Channels (Transmit Site)
Multiple Ship to Shore transmission channels (Received at Shore Receive Site)
Multiple Ship to Shore ARQ ack channels (Transmitted at Shore Transmit Site)
Use of Antennae optimized for transmission or reception
Some implications on Ship/Shore
Shore STANAG 5066 needs to drive two modems
Ship is Simplex (normal HF)
Shore is Half Duplex (collision detect possible)
Slide 6 of 24 Isodei
HF Naval Communication
Surface Wave HF used between Task Groups
Good propagation for hundreds of nautical miles
HF is an important BLOS communications channel for Navies
Backup to Satcom
Operation in Satcom-Denied and Satcom not available
When operational considerations avoid Satcom
Point to Point SkyWave enables ship/shore and ship/ship communication
Managing pool of frequencies between ships means that links put in place “as needed”
“Alternating” transmit/receive of up to two minutes increases latency
Slide 7 of 24 Isodei
Why the BRASS Architecture is Good
Broadcast is a very sensible approach to Naval HF communication
Shore to Ship is dominant information flow
Many messages go to multiple ships, so natural optimization of slow data link
No delays as data flow is continuous
Can use optimized shore based transmitters
Broadcast can be sent simultaneously on multiple frequencies
Different ships may be seeing different propagation characteristics
Broadcast makes sense as long term HF Naval Strategy
Need to evolve the details of how it is done
Slide 8 of 24 Isodei
Current HF Technology for BRASS
Typical deployed technology and requirements in current procurements
STANAG 4285 Modem: 75-2400 bps
STANAG 4197 (Voice)
Ship to Shore links set up by special mechanism (FAB)
Extensive operator involvement
Broadcast (and some Ship to Ship) operates application directly over modem
Lack of link level error checking causes horrendous problems for the layers above
A very long way from state of the art
Slide 9 of 24 Isodei
Current Messaging Technology for BRASS
Messaging based on ACP 127
Derived from Teletype protocols
No lower case letters
No protocol
Reliability achieved by process and human operators
ZCZCDEF231 HH PP RIJPODE RWRR 0238 2341302 ZNY SSSSS EX REFORGER P 221258Z AUG 14 FM CIC TO JPO BT S E C R E T SIC SIC SUBJ: GENERAL GRANT EXERCISE REFORGER NINE WHAT TIME IS GENERAL GRANT EXPECTED? DOES HE REQUIRE TRANSPORT TO THE NEXT VENUE?
BT NNNN
Slide 10 of 24 Isodei
Why is the BRASS Technology Ancient?
Fit for Purpose, so no driving reason to change
Interoperability with deployed systems is fundamental
Typical procurement focus
Systems build with components that do not give a path to new technologies:
Customs “one off” software developed by large Systems Integrator
“Free” NATO BRASS Software (BICC)
Procurements based on “least cost compliant” with no mandatory requirements to enable migration to newer technologies
Slide 11 of 24 Isodei
The Isode BRASS Plan
A COTS Solution to provide everything for BRASS above Modem
Support Modems with full range of modern capabilities, including WBHF
STANAG 5066
Messaging (ACP 127; ACP 142; STANAG 4406; SMTP with RFC 6477 and other military enhancements)
Messaging for BRASS to be covered in an upcoming Isode whitepaper
Support Legacy operation and give migration path to state of the art Messaging and HF technologies
Complete in Summer 2015
Lower total solution cost due to reduced integration costs
Slide 12 of 24 Isodei
How Current Broadcast Transmission Works
ACP 127 transmits character stream to Crypto
Splitter enables transmission over multiple frequencies at the same time
Ships can pick the frequency that propagates best to the ship
Slide 13 of 24 Isodei
Off The Air Monitoring (OTAM)
Without Link Layer (STANAG 5066) checksums, receiver cannot determine link quality
Receivers for OTAM are at Skywave distance from broadcast transmission
Receivers on land sites chosen to have reception similar to what ships will see
OTAM process compares transmitted (ACP 127) stream with received stream (from receiver getting transmission by Skywave)
If receive quality has error rate higher than configurable level, OTAM alert is generated
OTAM alert will cause management tool to switch broadcast to a different frequency
Switch enables one OTAM process to monitor multiple broadcast frequencies
Slide 14 of 24 Isodei
How Current Ship to Shore Works
STANAG 5066 used
Pool of HF Frequencies allocated to Ship to Shore
Connections always initiated by Ship
So not sensible to use link to send data from Shore to Ship
Shore broadcasts available frequencies and noise level on each Ship/Shore channel – “Frequency Availability Broadcast” (FAB)
Options for one channel (SIMPLE/IFAB) or two (DUPLEX/CFAB)
Ship picks a frequency to send on
Shore detects frequency is being used and updates the FAB
Helps avoid another ship using the frequency
Slide 15 of 24 Isodei
Serial Ports and Circuits
How the BRASS world currently thinks of configuration
Everything is a hardware box with two serial (or audio/RF) ports
ACP 127 and Antennae just have one port
Build circuits by connecting (serial) ports
Need to live with this to some extent (as many components currently do have two ports) but want to move towards modern world where:
Devices (even Crypto boxes) connect with Ethernet interfaces
Software can switch dynamically – external circuit configuration should not be needed
Slide 16 of 24 Isodei
Supporting Direct to Modem
Isode needs an approach to run ACP 127 direct over modem
For Broadcast and some Ship to Ship
Added mode to Icon 5066 (our STANAG 5066 server) to not do STANAG 5066 protocol over the modem and go direct to modem
Re-uses modem drivers in Icon 5066
Enables direct to modem using a TCP based modem interface
Avoids needing to put a serial port driver in our M-Switch ACP 127 Channel
ACP 127 connects using Character Oriented Streaming Service (COSS) in same way as for operation over STANAG 5066
Slide 17 of 24 Isodei
Serial Links & Circuit Management
Need to build Circuits to support current BRASS world
Tool to manage circuits (Antennae, Modems, Radios, Crypto, Serial Hubs) is needed
NATO systems call this “RSC” (Remote Supervision & Control)
Messaging Circuit end points are ACP 127 and ACP 142
Isode provides COTS API to add Messaging, OTAM, and Icon 5066 into circuits
M-Switch HF Circuit Management (MHFCM) API
Slide 18 of 24 Isodei
Improving HF Broadcast
Use STANAG 5066 (non-ARQ)
Use modern broadcast messaging (ACP 142 based)
Per Message Acks and FEC can optimize retransmissions (and latency)
Go Faster (STANAG 4539; WBHF)
Lower delays (avoids back-log)
Enables sending larger messages
Make intelligent use of multiple broadcast channels
Can do better than just sending the same data on each
Use knowledge of which frequencies reach which ship
Variable Speed
To make best use of higher speeds need to adapt to conditions
Need information on SNR and FER from each ship
Slide 19 of 24 Isodei
Variable Speed Broadcast Architecture
Use Ship to Shore links to send information from each ship back to shore
Only small amounts data
Link Quality information is the same as needed for STANAG 5066 Data Rate Change
Also need to indicate which frequency this information applies to
Shore system correlates information to determine
Which speed to use
Which frequency to send which messages on
Auto-baud Waveforms allow shore system to pick best speed and ships will adapt
Slide 20 of 24 Isodei
Improving Ship to Shore
Need to get small amounts of information (fairly) frequently from Ship to Shore:
Message Acknowledgments
Ship Broadcast Reception Quality
As well as real messages from Ship to Shore
Can do better than FAB
There are not usually enough frequencies for each ship to have a dedicated ARQ link
ALE is an obvious direction
Perhaps use STANAG 5066 Annex L Wireless Token Ring
Shore in each “ring” Use multiple (fixed frequency) rings to keep ring size moderate
Slide 21 of 24 Isodei
ALE for BRASS
Could use standard ALE or an approach optimized for BRASS architecture
Aspects of the FAB design make sense
Unclear which is the best approach
Use the broadcast channel to share channel information in the way FAB does
Should run FAB+ over STANAG 5066 non-ARQ
Could multiplex FAB+ with messages on single broadcast channel
Could use FAB+ to communicate shore-initiated requests for Ship-Shore links
Multiple shore transmitters allows possible new frequencies to be tested easily
Shore to Ship propagation information could be easily shared on Ship to Shore communication (same information as for variable speed broadcast)
Ship to Shore could be used to schedule reservations
Reservations can be shared over FAB+
Could work for Ship-Shore and Ship-Ship
Slide 22 of 24 Isodei
Annex L Pool for Ship to Shore
STANAG 5066 Annex L gives multi-node communication using Token Ring
Will enable efficient sharing of a single frequency between a group of ships
Address limited number of frequencies for Ship-Shore and Ship-Ship
Potential advantage of enabling other communication in the group of ships (and shore) which point to point (set up by ALE) does not
Slide 23 of 24 Isodei
Organizational Messaging (ACP 127 Service with modern protocols) remains central
Use ACP 142 to support STANAG 4406, SMTP with military extensions and EMCON (ships in Radio Silence)
Natural additions
XMPP Real Time Chat (e.g., NATO JCHAT+ Service)
Images and Documents (as message attachments)
Probably Achievable with Narrow Band HF
Video (as message attachment)
Voice memos (“push to send” style)
With WBHF
Video Streaming to Ships
Applications for Future BRASS
Questions?
Isode